118 STUDIES IN GENERAL PHYSIOLOGY 
Almost all the numerous other authors who have worked 
upon the regeneration of organs in animals also regard it as 
self-evident that the regenerated organ’ must be identical 
with the lost organ in form and function. The facts which 
I shall bring forward in the following pages will show, how- 
ever, that this theory is certainly too narrow. For I suc- 
ceeded in doing away with “polarity”’ first of all in that 
very animal upon which Allman based his theory of 
‘‘polarity’’—namely, in Tubularia. 
One of the first authors who concerned himself with 
the study of the phenomena of regeneration, Charles Bonnet, 
looked upon them in a less biased way than did Allman. 
Bonnet, to whom Trembley had very early communicated 
the fact of the phenomenal regenerating power in Hydra, 
attempted to convince himself of the truth of Trembley’s 
statements; since, however, he was unable to obtain Hydra, 
he tried whether similar results could not be obtained upon 
worms. Bonnet used two species of worms in his experi- 
ments. In the first species, which he designates as vers 
rougeatres, he found the conditions which are typical for 
Hydra, and which correspond to the theory of “polarity.” 
If the head of such a worm was cut off, a new head was 
formed at the cut end; when the tail was cut off, a new tail 
was formed at the point of section. If the head and tail 
were both cut off, a head was formed at the oral end, and a 
tail at the aboral end. In a second species, the vers 
blanchatres, the results were not so regular. When only 
the head or tail was cut off, the lost part was always 
regenerated. If, however, a piece was cut out of the middle 
of the worm, it happened that such a piece formed a tail at the 
oral end, instead of ahead. Bonnet observed this three times.’ 
I have found no reference in the literature which would 
indicate that these observations of Bonnet have ever been 
1CH. BONNET, Cuvres d'histoire naturelle et de philosophie (Neuchatel, 1779), 
Vol. I (Traité d’insectologie). 
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